In recent years, outdoor leisure activities, adventures, and tourism prevail, and networks and social networking sites are developed rapidly, so that outdoor activity lovers often organize outdoor activity groups such as mountaineering teams, adventure teams, cycling teams, motorcycle teams with a large number of members for long-distance outdoor activities.
As we all know, it is very essential to take safety into consideration for outdoor activities in addition to the arrangement of itinerary. However, in reality, accidents or events of missing team members are still seen. For example, a falling-behind member of a cycling team may have an accident, get lost, or lose contact, or a member of a mountaineering team or adventure team may be missing.
Among various accidents of the outdoor activity groups, the members of the mountaineering team or adventure team are most difficult to rescue or search. Since the itinerary of these activity groups is usually harsh, and these teams often go to an inaccessible environment that falls beyond the communication range of mobile phones, and the physical fitness of each member varies, so that the distance between the team members often exceeds the line of sight. If a member falls down in a valley unfortunately or loses direction, and other members have to wait for a long time at a gathering place which may be tens of kilometers away before the accident is discovered, and it is often too late to look back and search for the missing team member.
In addition, if the outdoor activity group searches in the opposite direction along the original path and still cannot find the missing team member, the only solution is to inform the rescue team through communications to go up to the mountain to search for the missing team member. However, the rescue team can only rely on the impression of other members, but cannot know exactly the location of the missing member. Therefore, it is often necessary to adopt a large-scale search in the mountain. If the weather is poor, then it will be very difficult to search and rescue the missing team member, and thus not just jeopardizing personal life and safety only, but also wasting lots of social resources.
To overcome the aforementioned problems, there are independent communications or warning systems of the existing technology designed for outdoor activity groups, such as those disclosed in R.O.C. Pat. Nos. 1446295, 1376652, 1553295, 1286420, M392493, etc. However, the biggest issue of these systems is that the obstacle caused by distance cannot be overcome in the absence of the Internet or telephones used for communicating with the outside world.
For example, if a mountaineering team is divided into a plurality of units, each consisting of a single member, two or more members, and the distance between any two units is 1-2 Km, and the number of mountaineering team members or the number of units exceeds 10, then the distance between the leading team member and the last falling-behind team member will exceed 10-20 Km. Obviously, the communications of the group is difficult. More importantly, in the event of losing contact, the search area will be hundreds of square kilometers. Searching in such vast and severe environment is just like searching needles in the haystack.
In the aforementioned prior arts, R.O.C. Pat. No. 1376652 uses the members' communication devices to connect with each other, so that the peripheral nodes of the group form a loop, and the inner peripheral nodes and outer peripheral nodes in the loop form a topological network. When any node in the topological network disappears, it indicates that the member holding the communication device may have an accident or may get lost.
Although the method above can control the status of each member more strictly, yet the required equipment cost, weight, and power of the communication devices in the topological network are not conducive to the mountain climbing activity of which members are lining up substantially in a straight line. Furthermore, a wireless communication module (such as WIFI or Bluetooth) required for an independent topological network has a maximum connection distance of only hundreds of meters, and thus it is inapplicable for the mountaineering team or cycling team having a relatively longer activity distance (up to tens of kilometers) between members.
In fact, a walkie talkie used for broadcasting RF signals by a public open frequency band has a transmission distance much greater than the transmission distance between the aforementioned communication devices. In addition the conventional walkie talkie does not need the Internet to transmit information, so that it has long been used as a contact device for an outdoor activity group. However, the conventional walkie talkie still has the shortcomings of insufficient distance and incapable positioning function.